Nordost sounds good in a wide variety of systems, so saying that its all relative and that only "in your system" answers are valid, is itself inaccurate.
Nordost tends to make a strong effect on the listener immediately - mostly because mechanical artifacts are so reduced significantly across the spectrum. This lends transients with a quickness and highs that are clean and extended without seeming threadbare. Many people who favor accurate cables love Nordost as a revelation because it is clean without emascalating the harmonics that their system already presents.
With that said, accurate systems, and the people drawn to them, do not seem to value harmonic complexity and spatial realism to the same degeee as others. It is with this group of people that Nordost generally falls down with, eventually.
Why say "eventually"? Because the things that Nordost does not do are generally subtractive in nature and address the deepest harmonic fabric and the nature of surrounding space, and these qualities are not generally discerned except upon extended listening, i.e. detail and accuracy are most easily heard from the state you are in when you first sit down to listen (call it identifying listening) and spatial/harmonic nuance is discerned most readily when you drift into the music and stop identifying (call it receptive listening).
Nordost tends to favor source points of sound over the space that surrounds them. This is not a cooky-cutter effect where space is a void (early digital's problem, among others)as with many early analytic IC's, but a relegation of space in relation to the source. Secondly, Nordost is more concerned with the energy of the leading edge transient than the depth of harmonic development in the core or decay of a note. The harmonic nature and the spatial nature, in tandem, of Nordost lead to a subtle disconnect between space and source that is not percieved except on systems that strive towards these qualities and over the long haul.
Its a good workhorse cable for the vast amount of systems out there, but does have its limits in, what I believe, are important areas. It are these areas of the deepest harmonic fabric and spatial continuity - and their intra-relationship as sound move through space - that are the most elusive at the highest levels, and what so-called state-of-the-art systems strive for as the last nuance that re-creates "reality" and allows one to fall into the Music.
I would submit that Nordost is a good cable, maybe a very good cable in many systems, but still reductive of a set of subtle, interrelated qualities that become progressively important as one goes on.